Instant messages are conversational in nature. To maintain their conversational character, instant messages typically are communicated in real time to a user based on an indication that the user presently is online. Nevertheless, the conversational nature of instant messaging may subject a user who is visible online to undesired real-time advances or interruptions from other online entities. For example, a user who enters an online chat room may be subjected in real-time to instant messages from other individuals, known or unknown to the user, as well as from commercial entities, some of whom may purvey undesirable spam. Having entered an instant messaging conversation with a friend, the user may find the conversation overwhelmed in a cacophony of competing instant messaging voices, each demanding the user's immediate attention. Although the user may use a knock-knock (e.g., a pop-up window that provide the user the option to accept or reject an individual instant message based, for example, on an identification of the sender) to screen instant messages from entities not on a contact list of the user, a knock-knock, like the instant message that it represents, is obtrusive and steals the focus of the user from other tasks or conversations that are at hand.